This invention relates to continuous extrusion apparatus for the forming of metals by a continuous extrusion process in which feedstock is introduced into a plurality of circumferential grooves in a rotating wheel to pass into passageways formed between the grooves and arcuate tooling extending into the grooves.
WO96/29162 discloses continuous extrusion apparatus for the production of copper tubing having a rotatable wheel formed with a plurality of circumferential grooves provided with exit apertures in a die top and abutments displaced in the direction of rotation from the exit apertures.
According to the present invention, each of the plurality of circumferential grooves is provided with an exit aperture in the die top having a cross-sectional area in excess of twice the radial cross-sectional area of the associated groove and smoothly leading to a passage of minimum length to connect into an annular extrusion die.
Preferably, the exit aperture has a cross sectional area of three times the radial cross-sectional area of the associated groove.
Suitably, the exit aperture has a cross-sectional area of four times the radial cross-sectional area of the associated groove.
Desirably, the exit aperture has a cross-sectional area of five times the radial cross-sectional area of the associated groove.
The invention also includes an extrudate product in the form of a continuous, seamless, copper tube having a mass in excess of 500 kilograms.
It will be understood that the term seamless relates to copper tube formed as a tube by an extrusion process as distinct from a copper tube formed by edge joining a strip or strips along abutting edges.